/*
 * Copyright 2014 Netflix, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.netflix.servo;

import com.netflix.servo.monitor.MonitorConfig;
import com.netflix.servo.tag.TagList;
import com.netflix.servo.util.Preconditions;

/**
 * Represents a metric value at a given point in time.
 */
public final class Metric {
  private final MonitorConfig config;
  private final long timestamp;
  private final Object value;

  /**
   * Creates a new instance.
   *
   * @param name      name of the metric
   * @param tags      tags associated with the metric
   * @param timestamp point in time when the metric value was sampled
   * @param value     value of the metric
   */
  public Metric(String name, TagList tags, long timestamp, Object value) {
    this(new MonitorConfig.Builder(name).withTags(tags).build(), timestamp, value);
  }

  /**
   * Creates a new instance.
   *
   * @param config    config settings associated with the metric
   * @param timestamp point in time when the metric value was sampled
   * @param value     value of the metric
   */
  public Metric(MonitorConfig config, long timestamp, Object value) {
    this.config = Preconditions.checkNotNull(config, "config");
    this.timestamp = timestamp;
    this.value = Preconditions.checkNotNull(value, "value");
  }

  /**
   * Returns the config settings associated with the metric.
   */
  public MonitorConfig getConfig() {
    return config;
  }

  /**
   * Returns the point in time when the metric was sampled.
   */
  public long getTimestamp() {
    return timestamp;
  }

  /**
   * Returns the value of the metric.
   */
  public Object getValue() {
    return value;
  }

  /**
   * Returns the value of the metric as a number.
   */
  public Number getNumberValue() {
    return (Number) value;
  }

  /**
   * Returns true if the value for this metric is numeric.
   */
  public boolean hasNumberValue() {
    return (value instanceof Number);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean equals(Object obj) {
    if (obj == null || !(obj instanceof Metric)) {
      return false;
    }
    Metric m = (Metric) obj;
    return config.equals(m.getConfig())
        && timestamp == m.getTimestamp()
        && value.equals(m.getValue());
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public int hashCode() {
    int result = config.hashCode();
    result = 31 * result + (int) (timestamp ^ (timestamp >>> 32));
    result = 31 * result + value.hashCode();
    return result;
  }


  /**
   * {@inheritDoc}
   */
  @Override
  public String toString() {
    return "Metric{config=" + config + ", timestamp=" + timestamp + ", value=" + value + '}';
  }
}
